NEW AMPHIPHILIC IMMUNOGENS BY CU2-MEDIATED COMPLEXES OF WATER-BORN POLY(N-ISOPROPYLACRYLAMIDE) AND BOVINE SERUM-ALBUMIN()

Cu2+-mediated complex formation between temperature-responsive poly(N- isopropylacylamide-co-acrylic acid) (CP) and bovine serum albumin (BSA ) was investigated in neutral and in physiological salt solutions. Wat er soluble or insoluble ternary complexes are formed upon addition of divalent copper ions to the solution. Stability of the ternary polycom plexes depends on the composition of the copolymers, concentration of copper ions and ratio of components. Stimuli-sensitive (temperature, p H-and ionic strength-) behavior of CP, CP-Cu2+ and CP-Cu2+-BSA solutio n was studied. The ternary CP-Cu2+-BSA complexes exhibit reversible te mperature-responses in physiological salt solutions at suitable ratios of the components. Thermal collapse of ternary polycomplexes was obse rved in higher pH solutions than for CP and CP-Cu2+. The negative temp erature solubility coefficient in salt containing solutions may be due to cooperative hydrophobic interactions. Cu2+ in 0.154 M NaCl solutio ns of CP with BSA, in contrast to CP-Cu2+ BSA complexes in water, gave increased BSA-specific immunogenicity. A single immunization of mice with ternary CP1-Cu2+-BSA complexes in physiological salt solutions wi thout adjuvant increased the specific immune response to BSA. The high est level of immunogenic activity was after a second immunization whic h lasted more than 18 months. The highest immunogenic activity was exh ibited by stable ternary complexes, and immunoactive polycomplexes wit h a negative temperature solubility coefficient. A hypothetical struct ural model for the formation of ternary polycomplexes and mechanism fo r the manifestation of immunological activity are presented.